Expression of interleukin (IL)-12 mRNA in gastric carcinoma specimens: cellular antitumor immune responses.
OBJECTIVE
Several tumor-related antigen peptides that are recognized by autologous cytolytic T cells (CTL) have been reported. However, most human solid tumors, including gastric carcinoma, are only weakly immunogenic. In this study, we focused on interleukin (IL)-12 and interferon-gamma (IFN-gamma) as key cytokines for estimating positive cellular immune responses.


METHODS
To estimate the immunogenicity of gastric carcinomas, we examined IL-12 and IFN-gamma at mRNA levels by reverse transcription-polymerase chain reaction assay (RT-PCR) in tumor specimens and adjacent nontumor specimens from 36 gastric carcinoma patients.


RESULTS
IL-12 expression was detected in 12 tumor specimens and in only two adjacent nontumor specimens (P = .003). The frequency of IFN-gamma gene expression was higher in the IL-12 mRNA-positive tumor specimens than in the IL-12 mRNA-negative tumor specimens (P = .015). In the IL-12 mRNA-positive tumors, IFN-gamma expression was higher in the tumor specimens than in the adjacent nontumor specimens (P = .007). Conversely, in the IL-12 mRNA-negative tumors, IFN-gamma expression was lower in the tumor specimens than in the nontumor specimens (P = .03). Many tumor-infiltrating mononuclear cells, predominantly T cells, were found in four of the 12 IL-12-mRNA-positive tumor specimens and in none of the 24 IL-12-mRNA-negative tumor specimens (P = .008).


CONCLUSIONS
These data suggest that possible immune responses against a tumor may occur at the mRNA level in approximately one-third of gastric carcinomas.
Katano
M
M
Department of Surgery, Saga Medical School, Japan. Katano@post.saga-med.ac.jp
Nakamura
M
M
Kuwahara
A
A
Fujimoto
K
K
Matsunaga
H
H
Miyazaki
K
K
Morisaki
T
T
D015139:Blotting, Southern; D004587:Electrophoresis, Agar Gel; D015870:Gene Expression; D006801:Humans; D007111:Immunity, Cellular; D007371:Interferon-gamma / Q000235:genetics*; D018664:Interleukin-12 / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis; D012194:RNA-Directed DNA Polymerase; D013270:Stomach / Q000276:immunology; D013274:Stomach Neoplasms / Q000235:genetics / Q000276:immunology* / Q000473:pathology
D012333:RNA, Messenger; D018664:Interleukin-12; D007371:Interferon-gamma; D012194:RNA-Directed DNA Polymerase